This invention relates in general to a gas distributor flute designed to provide uniform gas flow in the trays or packing of a fractionation column, such as in a hydrocarbon processing facility.
More specifically, the present invention relates to a device that conditions ultra high entrance velocity feed gases, which also include liquids and/or solids, from a single or multiple feed nozzles to a quiescent flow regime for uniform distribution of the gases, liquids and solids to a contact device within a distillation or fractionation column. The present invention allows for the disengagement of the gaseous flow from the liquid flow while effectively and concomitantly accommodating separation of (high) solids from the multiphase vapor flow.
Vapor, liquid and solid interaction occurs in many types of mass transfer and heat exchange processes. Typically, a vapor stream is introduced into a separation column below a region containing trays or random or structured packing while the liquid stream is introduced into the column above the trays or packing. The vapor and liquid streams then flow in countercurrent relation through the region, with the trays or packing serving to distribute the downwardly flowing liquid stream over a larger surface area to enhance the mass heat transfer interaction with the upwardly flowing vapor stream.
In order to increase the efficiency of the mass transfer or heat exchange taking place between the vapor and liquid streams, it is important that the vapor be uniformly distributed across the horizontal cross-section of the column, particularly at the lower vapor-liquid interface where the vapor enters the packing. When the vapor is introduced to the column below the packing, the velocity of the vapor can prevent the desired horizontal distribution of the vapor prior to its entry into the packing. In order to improve the vapor distribution, deflectors have been positioned in some columns in the flow path of the vapor to deflect the vapor in a plurality of directions.
Another problem with the prior art processes is that there is often a need to separate entrained or slugs of liquids and solids from the gaseous feed(s) to fractionation towers. In the prior art this typically has been accomplished by the use of a knockout drum placed upstream of the fractionation tower. The purpose of this procedure is to keep unwanted liquid and solid contaminants out of the absorption or distillation process. The use of the knock out drum, however, adds to the complexity and cost of the process by adding another piece of equipment. It would represent an advancement in the state of the art and solve a long felt need in the art if the knock out drum could be eliminated and the liquids and solids could be removed internal to the separation column.
An example of a conventional vapor distributor, known as a vapor horn, is disclosed in U.S. Pat. No. 5,106,544 (incorporated herein by reference). The vapor horn disclosed in that patent comprises an annular housing that is open at the bottom. The vapor horn contains a plurality of vanes that extend upwardly at progressively greater distances into the housing through the open bottom causing downward deflection of the circumferentially flowing vapor stream. The downwardly deflected vapor then is said to rise in a uniform manner into a packing bed that is positioned radially inwardly from the vapor horn.
While circumferential vapor horns can function satisfactorily in many applications, it has been determined that a poor distribution of the vapor stream may result under certain operating conditions. This poor distribution is believed to be caused by the vapor stream traveling through a swirling or cyclonic flow path after it is discharged from the vapor horn. A low velocity zone is created in the center of the column and a high velocity zone is created adjacent the inner wall of the vapor horn as a result of this cyclonic vapor flow. These velocity differentials reduce the amount of vapor entering the center portion of the overlying packing and increase the amount of vapor in the radial outer portions of the packing. Once the vapor has entered the packing, this poor distribution of vapor cannot be corrected readily and reduces the efficiency of the mass transfer occurring within the trays or packing.
U.S. Pat. No. 5,605,654 (incorporated herein by reference) describes a method and apparatus for a vapor distributor that is capable of separating gaseous and liquid medium by circulating a vapor stream about an inner periphery of a column. The vapor stream is discharged from the distributor through an at least partially open bottom and, optionally, a plurality of spaced apart outlet ports in an inner annular wall of the distributor. A deflector extends upwardly along the inner annular wall to deflect the vapor stream away from a circumferential flow path along the inward face of the wall. The deflector also may extend outwardly under the flow channel to deflect, in a radially inward direction, vapor exiting the flow channel through the open bottom of the distributor. U.S. Pat. No. 5,632,933 (incorporated herein by reference) describes a vapor distributor having a deflecting surface that directs a vapor stream about the inner periphery of a column. The vapor horn of this device employs deflectors spaced throughout a vapor flow path to alter the direction and speed of a gaseous and liquid medium.
The need exists in the art for a vapor distribution device that can separate solid, liquid and gaseous mixed phases and provide a uniform distribution of vapor to the trays or packing in a column. The prior art does not teach a device that is capable of separating all three phase when they are introduced simultaneously from a feed nozzle into a column for fractionation and/or other chemical processing.
While conventional vapor distributors can function satisfactorily in many applications, a need has arisen for an improved vapor distributor that will provide a more uniform distribution of vapor across the horizontal cross-section of a mass transfer or heat exchange column.